1. Technical Field
The present invention relates to a method for preparing a carbon dioxide absorbent based on natural biomass, and a carbon dioxide absorbent based on natural biomass that is prepared by the method. More particularly, the present invention relates to a method for preparing a carbon dioxide absorbent that utilizes alkali metal or alkaline earth metal components, such as Ca, Ma and K, inherent to a natural plant biomass material, thus enabling the preparation of a highly efficient carbon dioxide absorbent at low cost.
2. Description of the Related Art
Carbon dioxide is a major cause of global warming and its concentration in the atmosphere has been sharply increasing since the Industrial Revolution. The carbon dioxide issue is considered a global problem through the Rio Declaration on Environment and Development and the Kyoto Protocol, and solutions to solve this problem have been actively studied.
Carbon dioxide sources are usually flue gases released from the burning of fossil fuels, synthetic gases produced during coal gasification, and synthetic gases produced during natural gas processing. Many methods for removing carbon dioxide are known, for example, wet chemical absorption, adsorption, membrane separation and low temperature distillation. However, these methods incur high costs and are thus difficult to commercialize.
According to a known method for removing carbon dioxide from a gas stream using a dry sorbent, an active component present in the solid sorbent is allowed to chemically react with carbon dioxide to produce a carbonate or bicarbonate. The sorbent can be regenerated and reused after heating in a regeneration reactor. The dry sorbent should meet the following requirements: 1) inexpensive materials, 2) easy regeneration, 3) applicability to low energy absorption processes, and 4) the ability to remove carbon dioxide present at a very low concentration. Other requirements for the dry sorbent are environmental friendliness, good absorptivity for carbon dioxide, and high reaction rate. Further, the dry sorbent should be made of a physically or chemically durable material.
U.S. Pat. No. 6,387,337 issued to the United States Department of Energy (DOE) suggests a method for preparing a dry sorbent using an alkali metal or alkaline earth metal compound deposited on a support. Further, Korean Patent No. 620546 discloses the preparation of a dry sorbent that uses an alkali metal or alkaline earth metal compound as an active component to increase the removal efficiency of carbon dioxide. According to this patent, the dry sorbent is prepared by dispersing a sorbent composition essentially composed of an active component, a support and an inorganic binder in water to prepare a slurry, molding the slurry in a spray dryer to prepare a granular absorbent, and calcining the absorbent. However, the above patents are based on the ability of alkali metals and alkaline earth metals to absorb carbon dioxide and are associated with artificial addition of the corresponding components for the dry carbon dioxide absorbents. No study has been, to our knowledge, reported on a technology for removing carbon dioxide utilizing alkali metals and alkaline earth metals inherent to natural biomass materials.
Thus, the present inventors have continued to investigate a method for preparing a high performance carbon dioxide absorbent in an environmentally friendly and economical manner without artificial addition of alkali metals and alkaline earth metals. As a result, the present inventors have succeeded in developing a method for preparing a high performance carbon dioxide absorbent that utilizes natural alkali and alkaline earth metals inherent to a natural biomass material, contributing to cost reduction.